c#给com传入istream,居然取不出来

Question

c#端代码
MyIStream ms = new MyIStream();
ms.Write();
//MyIStream派生于MemoryStream和IStream
//即class MyIStream : MemoryStream, IStream
//ms.write调用的是下面函数
// public void Write()
// {
//            byte[] bb=new byte[3];
//            bb[0]=6;
//            bb[1]=1;
//            bb[2]=2;
//            Write(bb, 0, 3);          
//        }ms.Seek(0, SeekOrigin.Begin);
TESTLib.BBClass bb = new TESTLib.BBClass();
bb.pic(ms);com端代码
STDMETHODIMP BB::pic(LPUNKNOWN Stream)
{
AFX_MANAGE_STATE(AfxGetStaticModuleState()) CComQIPtr<IStream> pStream = Stream;
CFile fFile; ULARGE_INTEGER ulnSize;
LARGE_INTEGER lnOffset;
lnOffset.QuadPart = 0;
pStream->Seek(lnOffset, STREAM_SEEK_END, &ulnSize);
pStream->Seek(lnOffset, STREAM_SEEK_SET, NULL);
if(fFile.Open(_T("c:\\test.txt"), CFile::modeCreate | CFile::modeWrite))
{ char *pBuff = new char[ulnSize.QuadPart];
ULONG ulBytesRead;
ULARGE_INTEGER aa;
//pStream->Seek(lnOffset, STREAM_SEEK_SET, &aa);
if(pStream->Read(pBuff, ulnSize.QuadPart, &ulBytesRead)!= S_OK) 
{
delete pBuff;
// return S_OK;
}
/************************/
//取出来的pbuff为空,但ulBytesRead读出来了为3
fFile.Write(pBuff, ulBytesRead);
fFile.Close();
delete pBuff;
}
return S_OK;
}

Answer 1

.NET 的STREAM 和 COM的STREAM 不是一个东西，不能直接互用
试传
SafeArray or byte[]
或者你的mystream 实现  ISTREAM 接口，且表极为COM的

Answer 2

to:hdt(倦怠)我的mystream 是自己实现的com的istram
 
[ClassInterface(ClassInterfaceType.AutoDispatch)]     class MyIStream : MemoryStream, IStream
    {
        public MyIStream()
            : base()
        {
            
        }
        #region IStream 成员
        public void Clone(out IStream ppstm)
        {
            throw new Exception("The method or operation is not implemented.");
        }
        public void Commit(int grfCommitFlags)
        {
            throw new Exception("The method or operation is not implemented.");
        }
        public void CopyTo(IStream pstm, long cb, IntPtr pcbRead, IntPtr pcbWritten)
        {
            throw new Exception("The method or operation is not implemented.");
        }
        public void LockRegion(long libOffset, long cb, int dwLockType)
        {
            throw new Exception("The method or operation is not implemented.");
        }
        public void Read(byte[] pv, int cb, IntPtr pcbRead)
        {
//            throw new Exception("The method or operation is not implemented.");
            long bytesRead = Read(pv, 0, cb);
            if (pcbRead != IntPtr.Zero)
                Marshal.WriteInt64(pcbRead, bytesRead);
        }
        public void Revert()
        {
            throw new Exception("The method or operation is not implemented.");
        }        public void Seek(long dlibMove, int dwOrigin, IntPtr plibNewPosition)
        {
            //throw new Exception("The method or operation is not implemented.");
            long pos = base.Seek(dlibMove, (SeekOrigin)dwOrigin);
            if (plibNewPosition != IntPtr.Zero) 
                Marshal.WriteInt64(plibNewPosition, pos);                     
        }
        public void SetSize(long libNewSize)
        {
            throw new Exception("The method or operation is not implemented.");
        }
        public void Stat(out System.Runtime.InteropServices.ComTypes.STATSTG pstatstg, int grfStatFlag)
        {
            throw new Exception("The method or operation is not implemented.");
        }        public void UnlockRegion(long libOffset, long cb, int dwLockType)
        {
            throw new Exception("The method or operation is not implemented.");
        }        public void Write(byte[] pv, int cb, IntPtr pcbWritten)
        {
            Write(pv, 0, cb);
            if (pcbWritten != IntPtr.Zero) 
                Marshal.WriteInt64(pcbWritten, (Int64)cb);        }
        public void Write()
        {     
            byte[] bb=new byte[3];
            bb[0]=6;
            bb[1]=1;
            bb[2]=2;
            Write(bb, 0, 3);         
        }        #endregion
    }

Answer 3

现在是能传到com,
可com传不出来,唉

Answer 4

详见
http://community.csdn.net/Expert/topic/5340/5340086.xml?temp=.9813959